Bursa Fabricii

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The Bursa Fabricii or Bursa cloacalis is a sack-shaped lymphatic organ found in birds on the roof of the cloaca . This organ is used for the primary differentiation of the B lymphocytes , which were first discovered in birds and which were given the addition "B" after the organ. The organ is named after Girolamo Fabrizio , who first described it in 1621. The organ's role in the immune system was recognized by Bruce Glick and co-workers in 1956 .

Structure, development, function and clinical significance

The Bursa Fabricii is a blind sac that extends from the end of the cloaca (the so-called proctodeum ). It has a slit-shaped opening in the roof of the sewer. This leads into a cavity divided by folds. The folds have a highly prismatic epithelium . Under the epithelium are follicles with a cortex and a medulla , with a basement membrane in between . The follicles consist mainly of lymphocytes , and macrophages are also found in the marrow .

The Bursa Fabricii is only active in young birds and regresses with the onset of sexual maturity ( involution ). Then the B-lymphocytes multiply in the other lymphatic organs. An early removal of the Bursa Fabricii leads to the fact that no B-lymphocytes are formed and thus to a functional failure of the immune system . The infectious bursal disease of chickens is a viral disease, which is associated with inflammation of the bursa of Fabricius. The depth of the bursal cavity decreases during involution, which can be used to estimate the age of some wild birds.

Bursal equivalent organs

Since the bursa fabricii is not developed in mammals , it has long been a mystery where the primary differentiation of the B lymphocytes takes place in these mammals . Even today, this problem has not been finally resolved, since different organs apparently perform this function depending on the species. Therefore one speaks of the bursal equivalent organ . In humans and mice this is the bone marrow (the English word for bone marrow - b one marrow - goes well with B lymphocyte), in the human fetus the liver, in ruminants the Peyer's plates of the intestine. For many other mammals, the bursa equivalent is still unexplained.

Individual evidence

  1. ^ A b R. L. Taylor, FM McCorkle: A landmark contribution to poultry science - Immunological function of the bursa of Fabricius. In: Poultry science. Volume 88, Number 4, April 2009, pp. 816-823, doi : 10.3382 / ps.2008-00528 , PMID 19276427 .
  2. ↑ B. Glick, TS Chang and RG Jaap: The bursa of Fabricius and antibody production. Poult. Sci. 35 (1956), pp. 224-225.
  3. ↑ Hans-Georg Liebich: Functional histology of domestic mammals and birds. Schattauer Verlag, 2010, ISBN 9783794526925 , pp. 171–172.
  4. ↑ Rolle / Mayr (ed.): Medical microbiology, infection and epidemic theory . Enke Verlag Stuttgart, 8th edition 2007, p. 226. ISBN 3-8304-1060-3
  5. ^ Nova J. Silvy: The Wildlife Techniques Manual . Volume 1: Research . JHU Press, 2012, ISBN 9781421401591 , p. 213.
  6. ↑ a b Stefan HE Kaufmann: organs of the immune system . In: Medical Microbiology and Infectiology , pp. 44–47.